Iphone 4 (verizon) shuts down by itself for no reason. reasons why?
I have had the Iphone 4 from Verizon since April 2011, it has worked great most of the time. Oddly enough it has turned off by itself for some strange reason. Any possible reasons why this keeps occuring? I have done everything well to maintain it- do the itunes/apple software updates, has 4 GB of free space. I finally learned how to reset it and that thank god has worked. But just today it shut down after I was sending an e-mail.. and ofcourse I'm traveling via airplane on friday and will need it!! bad timing... any help please.
iPhone 4, iOS 4.3.3, Verizon model